Raleigh 1977-79 Grand Prix paint question

[Geppy]

Hi,   I had a 78 or 79 Raleigh  Grand Prix that was very deep blue almost purple.  I have a frame from a 77 here that is the same color.   I also have a 76 and 81 frame and they are a slightly I mean slightly lighter blue.  Most people would not even notice as it so slight but my old one and the 77 are ever so  slightly darker and richer like you could fall into it. Any ideas on matching paint for touch up??  thanks Keith